1. Field of the Invention
The present invention relates to a high frequency power amplifier and particularly to a high frequency power amplifier usable for a transmitter in a communication system such as a cellular phone.
2. Description of Related Art
In recent and future years, code multiplexing is performed for signals transmitted by a so-called third generation cellular phone for the purpose of acceleration and sophistication of data. In this case, there occurs an increase in a ratio of maximum momentary power to an average power (peak factor). Consequently, distortion occurring in a power amplifier increases to increase an adjacent channel interference. There may be a case of providing acceleration by keeping the code multiplexing count constant. In such case, there arises a need to increase the transmission power so as to keep the S/N ratio constant in a reception portion. In this case, an average power increases to increase the gain compression applied to a maximum momentary power portion and to increase the distortion power.